Endovascular procedures are being used more and more frequently to treat various cardiac and vascular surgical problems. Blocked arteries can be treated with angioplasty, endarterectomy, and/or stenting, using minimally invasive endovascular approaches. Aneurysms can be repaired by endovascular techniques. Another use for endovascular surgery is the treatment of cardiac valvular disease. Valvuloplasties are already being done endovascularly and percutaneous valve replacement is being tested in the United States and two devices are already approved for use in Europe. A major problem which is common to all these endovascular manipulations is that plaque found in the diseased vessels and valves can be dislodged and result in embolization. A major drawback to endovascular treatment of cardiac valves or the thoracic aorta is that the dislodged debris can embolize into the carotid vessels resulting in catastrophic consequences such as stroke or even death. Any procedure involving the passage of catheters across the aortic arch carries this risk of causing carotid emboli. Attempts have been made to protect the cerebral vasculature with filters and other devices. The majority of devices described are filters. The problems with filters include difficulty in placement and retrieval as well as the possibility that a filter will fill abruptly causing blockage of the artery prior to removal of the filter. Cerebral protection requires placement of filters in the carotid arteries, which has the additional drawback of manipulation of the carotid vessels during filter placement while the cerebral vasculature is still unprotected. The risk of stroke for a carotid arteriogram done by cannulation of the carotid artery is 1% compared to an arteriogram done from injection into the aorta without selective cannulation which carries minimal risk. The risk of cannulating a carotid artery, navigating a catheter containing a filter into position, and deploying the filter would likely carry an even higher stroke risk. Patients requiring cardiac or aortic arch procedures are high risk candidates for having carotid disease. These procedures simultaneously place both carotid arteries at risk for emboli. The chance of causing a stroke by the placement of a protective device into both carotid arteries makes the risk of using these devices prohibitive. The time and skill necessary to selectively cannulate both carotid arteries for filter placement has also contributed to the decision not to use them despite the stroke risk of unprotected cardiac and aortic arch procedures.
Only a small number of devices have recently been developed which are designed to protect both carotid arteries at the same time. One device to date has come to market which protects both carotid arteries from emboli. The Edwards Lifesciences' EMBOL-X is a device designed for use in open heart surgery during cardiopulmonary bypass. The device is a filtering screen inserted directly into the ascending aorta immediately beyond the heart, similar to a dryer vent screen. This screen filters all blood exiting the heart and bypass machine prior to allowing it to pass to the downstream circulation. Limitations of this device include its applicability only to open heart surgery, excluding its use in the vast array of endovascular procedures requiring protection. Adoption of the device has been hampered by ease of use, as operators often find it cumbersome. The device could not be adapted to endovascular procedures as the EMBOL-X completely spans the aorta. Thus wires or catheters could not pass by it without breaking its protective seal. It has found limited adoption, and is chiefly employed for high risk patients undergoing open heart surgery. NeuroSonix Ltd. has developed the EmBlocker™, an ultrasound based scheme to deflect emboli away from the cerebral circulation during open cardiac procedures. An ultrasound probe is placed through the sternal wound and ultrasonic energy is directed at the blood flow in the aortic arch with the intent of deflecting emboli away from the cerebral circulation. Another proposed version for use in endovascular procedures is in the form of an externally applied “collar” around the neck of the patient, which would apply ultrasound through the neck with the hope of deflecting embolic particles away from the carotid circulation. It is known that the ultrasound beam can be tolerated only for brief periods of time and that it is turned off and on at different points during procedures. Thus there would be a lack of complete protection from beginning to end of an open heart procedure or endovascular procedure.
One additional device being developed for aortic embolic protection is the SagaX AEPD which is placed in the aorta through a femoral artery and secured in position with wire bows pressing against the wall of the aorta and another vessel wall. A key difference and disadvantage of this device is that, when it is positioned to cover the vessels of the aortic arch, one of its bows spans the aorta. Although a catheter from the index procedure might be able to pass through the open loop of the bow there is the possibility for entanglement, of dislodging the device, or of pressing against the bow causing damage to the aortic wall. Another difference and disadvantage of this device includes its delivery through the as yet unprotected aorta. The device is delivered across the aortic arch, which could cause emboli, and is manipulated into position in the arch with deployment of its bows against vessel walls while the aorta is unprotected. Other differences and disadvantages include possible difficulty in positioning, difficulty in sealing it in position, and possible trauma to the vessel walls from the pressure of the bows.
The Embrella Device described in this patent is an embolic protection system intended to reduce the amount of embolic material that may enter the carotid arteries during endovascular procedures involving the passage of catheters across the aortic arch. It may also be used for other endovascular procedures and open surgical procedures. It has many advantages for use with endovascular cardiac and aortic procedures. It is placed through an artery of the arm separate from the femoral insertion site of index procedure catheters and devices. It uses a 6 French sheath. It is easy to place using standard Seldinger technique. It is easy to deploy in the aorta where it self-aligns and can be secured in position covering the ostia of both the brachiocephalic and left common carotid arteries. It is able to be placed before the index procedure is begun and can remain in place, providing embolic protection, until the procedure is completed. It has a very low profile in the aorta so that wires, catheters, and sheaths can pass by it without interaction. It is able to deflect emboli greater than 100 microns in diameter away from the carotid arteries thus protecting the patient from potentially devastating neurological consequences of these emboli. Because it is designed so that one size fits all, it can be kept available in stock.